0.05 gph.
A pipeline system should not be declared tight if the test result indicates a loss that equals or exceeds this threshold.

Applicability

Gasoline, diesel, aviation fuel, fuel oil #4.
Other liquids may be tested after consultation with the manufacturer.

Specification

System tests fiberglass and steel pipelines.
Tests are conducted at 150% operating pressure.
Mechanical line leak detector must be removed or manually isolated from pipeline for duration of test, or if testing is to be conducted with mechanical line leak detector in place, check valve in pump must be manually closed.

Pipeline Capacity

Maximum of 426 gallons.

Waiting Time

None between delivery and testing. None between dispensing and testing.

Test Period

Under ideal conditions, 30 minutes; actual test time will depend on line size and temperature conditions at the site.
Data are collected every 15 minutes.
Three consecutive consistent readings are required for a valid test, with the first reading taken at zero time.
Test data are acquired and recorded manually.
Manual calculations performed by the operator on site.

Calibration

No temperature sensors used.
No calibration required.
System must be checked annually in accordance with manufacturer's instructions.
Technicians must be certified by the manufacturer prior to using this equipment and recertified every two years.

0.05 gph.
A pipeline system should not be declared tight if the test result indicates a loss that equals or exceeds this threshold.

Applicability

Gasoline, diesel, aviation fuel, fuel oil #4.
Other liquids may be tested after consultation with the manufacturer.

Specification

System tests flexible pipelines.
Tests are conducted at 150% operating pressure.
Mechanical line leak detector must be removed or manually isolated from pipeline for duration of test, or if testing is to be conducted with mechanical line leak detector in place, check valve in pump must be manually closed.

Pipeline Capacity

Maximum of 101 gallons (example: 275 feet of 3 inch line).

Waiting Time

None between delivery and testing. None between dispensing and testing.

Test Period

Under ideal conditions, 30 minutes; actual test time will depend on line size and temperature conditions at the site.
Data are collected every 15 minutes.
Three consecutive consistent readings are required for a valid test.
Data from the evaluation suggests that the actual minimum test time for a line this size is 2 hours.
Test data are acquired and recorded manually.
Manual calculations performed by the operator on site.

Calibration

No temperature sensors used.
No calibration required.
System must be checked annually in accordance with manufacturer's instructions.
Technicians must be certified by the manufacturer prior to using this equipment, and recertified every two years.

A tank system should not be declared tight when the acoustic signal detected is different from the baseline signal before a vacuum is placed on the tank, or when water ingress is detected by the water sensor.

Applicability

Gasoline, diesel, aviation fuel, fuel oil #4, waste oil.
Other liquids may be tested after consultation with the manufacturer.

Tank Capacity

Maximum of 30,000 gallons.
Ullage volume must exceed the greater of 1% of tank volume or 50 gallons.
Maximum of 30,000 gallons per tank for manifolded tank systems with microphone, water sensor and pressure monitoring gauges in each tank.

Waiting Time

None between delivery and testing.

Test Period

When groundwater level in tank excavation backfill is below bottom of tank:
A few minutes to determine background noise and about 2 minutes to run the test after desired vacuum is reached.
When groundwater level in tank excavation backfill is above bottom of tank or when the groundwater level in the tank excavation backfill has not been determined:
The time it takes for water ingress to increase the water level in the tank to allow the water sensor to detect the "minimum detectable change in water level" (see "Water Sensor" section below).
Test period based on water ingress is dependent on tank size. For example, the test period is 36 minutes for a 10,000 gallon (96" dia x324" lg) tank.
Before starting test, water sensor must be calibrated to "minimum detectable water level" (see "Water Sensor" section below) according to manufacturer's instructions.
There must be no dispensing or delivery during test.

Test Pressure

Pressure differential across tank wall at bottom of tank must be at least 0.5 psig.
Pressure differential across tank wall is equal to the absolute value of vacuum applied to tank, plus pressure of tank excavation backfill on tank, plus groundwater pressure on tank, minus pressure of liquid in tank.

Temperature

Acoustic signal is independent of product temperature.

Water Sensor

Conductivity water sensor must be used to detect water ingress and must be calibrated for every test when groundwater level in tank excavation backfill is above bottom of tank or when the groundwater level in the tank excavation backfill has not been determined.
Minimum detectable water level is 0.014 inch.
Minimum detectable change in water level is 0.0095 inch.
Minimum water level in tank must be adjusted to at least 0.014 inch (sensor's minimum detectable water level) before calibrating sensor and starting test.

Groundwater

Groundwater level in tank excavation backfill must be determined by observation well or soil probe in tank excavation backfill.
If groundwater level in tank excavation backfill is above bottom of tank or the groundwater level in the tank excavation backfill has not been determined, water sensor must be used and test time extended to ensure water ingress detection during test.

Comments

Microphone was 25 ft away from leak source during evaluation.
Although not tested on empty tanks, a third party acoustics specialist has certified the device is equally effective when tanks are empty as when tanks contain product.
Test may be inconclusive if there is high background noise.
Vacuum test method may not be effective in some tank excavation backfill (such as clay) because it may plug holes in tank.
If free product is present in tank excavation backfill, a leak in the free product zone may not be detected by a vacuum test method.
An observation well or soil probe in tank excavation backfill may help determine backfill material, water level in tank excavation backfill, and free product. Manufacturer must certify operator at least every 2 years.
More than 4 psi pressure differential across the tank wall at any location in the tank could damage tank.